How is the rackmount U-space of a NetShelter cabinet or rack identified?

Cause:
Incorrect placement of equipment can create airflow problems, like hot air recirculation.

Resolution: see below

As set forth by the EIA/ECA-310-E Standard:

1. For any Rackmount device or enclosure - a U or unit of rack space is equivalent to 1.75 inches or 44.45 mm.

2. The mounting hole pattern on a rack or enclosure must follow the following guideline:

Vertical Hole spacing must follow a pattern of 5/8""-5/8""-1/2"" or 15.9mm-15.9mm-12.7mm

Horizontal Hole spacing must be 18.3"" or 465 mm (+/- 1.6 mm)

Clearance between inner edges of mounting rails must be 450 mm at minimum

Outside edges of mounting rail must be 483.4 mm apart at minimum

EIA/ECA-310-E rail specifications in attached file.

To properly mount a device in the rack, a user needs to utilize the notched square mounting hole to indicate the center of a U space. For Example, to mount a 1 U device, 3 mounting holes would be covered by the device with the notched hole residing in the center of the group of 3. Mounting in an "off-U position", effectively moving the installed device 1 hole space up or down is incorrect and will lead to airflow and cooling issues.